This invention relates to assemblages of fasteners, and their manufacture, more particularly to assemblages of fasteners which are dispensable by machine for the tagging and attachment of articles.
Many different types of fasteners have been used for the tagging and attachment of articles. One such type, known as SWIFTACHMENTS.RTM., was introduced by the Dennison Manufacturing Company in 1963. The original SWIFTACHMENTS fasteners were in accordance with Bone U.S. Pat. No. 3,103,666, which issued Sept. 17, 1963 on assignment to Dennison. These fasteners were produced by molding an assemblage of individual fasteners, each with a thin filament interconnecting a cross bar with a head, and joined together by necks to a common runner bar. The SWIFTACHMENTS fasteners were dispensed using the SWIFTACHER.RTM. gun of U.S. Pat. No. 3,103,666.
A variation of the Dennison fasteners in U.S. Pat. No. 3,103,666 is disclosed in U.S. Pat. No. 3,185,367 which issued to F. L. Rieger et al on May 25, 1965 on assignment to the Monarch Marking Systems Company. However, the Rieger fasteners did not prove to be commercially successful, and Monarch later adopted fasteners of the Dennison type, as shown in Monarch's U.S. Pat. Nos. 3,650,451 and 3,650,452 which issued in 1972 to Weiland et al and Finke, respectively.
The Dennison fasteners were also widely adopted in foreign countries as illustrated by U.S. Pat. No. 3,652,004, which was issued to Batista Lozio on March 28, 1972 and claims priority from an Italian application.
After the development of the original SWIFTACHMENTS fastener it was discovered at Dennison that fasteners of the kind shown in its patent 3,103,666; in Monarch U.S. Pat. Nos. 3,650,451 and 3,650,452; and in Lozio U.S. Pat. No. 3,652,004 could be significantly and unexpectedly improved by being stretched in the vicinity of the junctions of their filaments with cross bars. In addition, to achieve satisfactory commercial production it was necessary to be able to stretch the individual fasteners of an assemblage simultaneously.
Although the stretching of extruded filaments, for example continuous nylon monofilaments, had been well known, the stretching of molded parts was not widely known at the time of the Dennison discovery. In addition, where the stretching of molded parts had been employed, it had been for intermediate sections. It was believed at that time that if a molded filament were subjected to stretching in the vicinity of a discontinuity, for example, the junction of the filament with a cross bar, there would be breakage. Instead, there was an unexpected strengthening of the filament at the junction, which forestalled the kind of filament breakage that had been encountered in using the earlier SWIFTACHMENT fasteners of the unstretched variety shown in U.S. Pat. Nos. 3,103,666; 3,650,451; 3,650,452 and 3,652,004. Stretched fasteners of the SWIFTACHMENTS type are now the most common in the merchandizing field and are now available from virtually all suppliers, including Monarch and Lozio.
Various methods for producing Dennison's stretched SWIFTACHMENTS fasteners are set forth in U.S. Pat. Nos. 3,380,122, issued Apr. 30, 1968; 3,444,597, issued May 20, 1969 and 3,457,589 issued July 29, 1969. As disclosed in those patents, the assemblages of fasteners are molded with slight tapers in a portion of their filaments in order to assure that the stretching will extend substantially to the junctions of the filaments with cross bars.
While the manufacturing methods disclosed in U.S. Pat. Nos. 3,380,122; 3,444,597 and 3,457,389 provide suitable fasteners, they require an appreciable time interval, e.g. cycle time, between molding and the completion of stretching. In addition, while the prior methods are eminently suitable for easily stretchable crystalline materials, such as nylon, they are less suitable for relatively rigid crystalline materials, such as polypropylene.
Accordingly it is an object of the invention to facilitate the production of assemblages of stretched fasteners for the tagging and attachment of articles.
Another object is to shorten the cycle time, and hence increase the production rate, for the manufacture of stretched fasteners.
A further object to achieve a method of manufacture which is of general applicability to the production of fasteners from crystalline plastic materials.